If you are looking for something more western( USA ) sounding then Kpop is choice, it has many similar beats and rhythms and the lyrics are easy to follow along. Kpop is my favorite.
Favorite Kpop band: Shinee
Jpop sounds like its for the younger crowd. Always reminds me of the Japanese Anime cartoons. Not something you want to have playing in your car when you are hanging out with friends. lol Jrock can be pretty cool though ^_^
Favorite Jpop band: Morning Musume http://www.youtube.com/watch?v=jjSR-NxOiv4
I wrote a couple of hubs on kpop check them out if interested.